Investigation on the Severity of Alternaria Blight of Pigeonpea and its Characterisation in Northern Karnataka

Abstract

Background: The Alternaria blight of pigeonpea is considered as an important foliar disease and poses threat to the pigeonpea cultivation due to change in the climatic condition, cultivation practices and variation in pathogenic character. Though the disease is noticed in an alarming proportion after the post rainy season and causing economic yield, little is known about the severity of disease and its impact on crop production. The current study is aimed to study the disease severity and variability of the pathogen and which would helps us to understand the biology of the pathogen to develop suitable management strategies. Methods: In the field and laboratory investigations during 2015 and 2017, different localities of Northern Karnataka were surveyed. Twenty sampling localities were selected based on geographical situation. In the laboratory, collected diseased samples were isolated and determined morphologically and culturally based on taxonomic and molecular characters. Result: Our investigations revealed the varied disease severity in surveyed districts, Vijayapura district recorded the maximum disease severity with a range of 38.67 to 49.33 and this might be due to variation in pathogenic character, rainfall pattern and climatic conditions and also disease severity varied with varieties indicating the source of resistance. The present study contributed for identification of geographical distribution of the disease and its severity in different varieties and places of Northern Karnataka and their genetic and morphological variations.

The Effect of Different Culture Media and Different Environmental Conditions on the Alternaria solani Sporulation

“…It was found that the plant interaction towards these factors includes stimulating a group of genes that express the occurrence of biochemical and physical changes within the plant, such as strengthening the cell walls through the deposition of lignin, suberin, and callus, as well as the production of phenolic substances, phytoalexins, and the Pathogenicity Related Proteins ( PRR) that prevent and inhibit the invasion of plant pathogens [29,30]. These results are consistent with many previous studies that confirm that the different media has a direct effect on the phenotypic characteristics of the fungus A. solani and the speed of mycelium growth, As some of these studies showed that the presence of large quantities of carbon present in carbohydrates stimulates it to produce mycelium, while the lack of carbon stimulates it to produce spores [21,31,32,33].…”